Author Topic: Shader: Glitter / Sequin (Pt.2)  (Read 2094 times)

2020-01-19, 08:53:25

cjwidd

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I have been exploring materials containing glitter / stochastic flakes recently and it has been a significant challenge for different reasons. Dubcat showed progress with a shader exhibiting glitter that was pretty compelling, but probably not similar to what could be achieved with stochastic flakes or similar shading effect.

I posted results for a semi-metallic material (see below) - my current best effort - that was meant to convey a glitter effect, but after extensive tests with various implementations of car paint shaders (i.e. Corona material library and Siger Studio), I am sort of curious whether it is actually technically possible to achieve a result comparable to V-Ray stochastic flakes with Corona Renderer?

Baroque

*semi-metallic wall covering processed from scan data



2020-01-20, 00:46:29
Reply #1

burnin

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Hm...
I wonder, when you write glitter (metallic flakes) or sequin alike, why does then your example appear to look like a textile mixed with a metal thread?
What are you really aiming at?
And please, rather provide a real world example with a link to a product...


« Last Edit: 2020-01-20, 00:50:14 by burnin »

2020-01-20, 01:06:58
Reply #2

cjwidd

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The example I included is meant to represent a textile with a metal thread, exactly as you described. However, what is not apparent in the render is that as the camera rotates around the model, there is a glitter effect - there is a flake layer inside a layered material. The example is not meant to represent glitter, or sequin, etc. it is only meant to illustrate the fact that I have made an effort to implement a glitter effect and have not been able to achieve a completely desirable result.

I am aiming for the effect that can be observed in the stochastic flakes link from the original post, however, I have not managed to create something even close to that, and it may not be technically feasible to do inside Corona at this time - it is not a rendering feature that is currently available. It would be good to know (absolutely) whether it is currently possible to achieve an effect like that with Corona, because if not I could just be spinning my wheels...

That being said, there are technical artists, and more generally artists with more experience, that might be able to create something like that in Corona, and so I am not willing to write off that possibility right away simply because I, personally, wasn't able to do it yet.

2020-01-20, 19:11:44
Reply #3

burnin

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Like this?


Note: Noise size and contrast modified to emphasize the sparkle effect.
Flakes are achieved with similar technique as that which is described in papers. But instead of circular flakes, i'm using cell voronoi noise (C4D) which drives normal map in a bump channel of a metal layer for a carpaint layered material (below).


« Last Edit: 2020-01-20, 19:16:53 by burnin »

2020-01-20, 21:21:42
Reply #4

cjwidd

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Right, this appears as a carpaint shader to my eye  which although it contains a shimmer effect, is not as pronounced as the glitter effect depicted in the stochastic flakes video from the original post.

I'm not sure if I really expect Corona Team members to say whether it is absolutely possible or not, at present, but I also didn't see anything about stochastic flakes on the dev log(?)

2020-01-20, 21:55:27
Reply #5

sprayer

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you mean like this?

2020-01-20, 22:32:21
Reply #6

cjwidd

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I must admit, that's pretty interesting. I wouldn't say it's exactly the same as the stochastic flakes implementation, but this is probably the best glitter I've seen in Corona. Nice work 👍
« Last Edit: 2020-01-21, 09:19:07 by cjwidd »

2020-01-20, 23:13:14
Reply #7

romullus

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I might be wrong, but i think stochastic flakes is a map, not a shader (don't have a V-Ray). Fundamentally there's nothing missing in Corona that would prevent you to replicate carpaint/glitter or whatever material. You might won't have as convenient control as procedural flakes map would give, but otherwise you should be totally fine.
I'm not Corona Team member. Everything i say, is my personal opinion only.
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2020-01-21, 00:11:18
Reply #8

cjwidd

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I'm inclined to agree with you, but I need to do more research into the SF implementation to know for sure. If that is the case, and it's just a map(?) - there is no shader magic happening behind it - that would be great news.


2020-01-21, 09:16:36
Reply #9

cjwidd

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I checked the example posted by sprayer more closely - previously I had looked at it on my phone - and looks like the reflection color is being mapped in addition to the bump?

2020-01-21, 11:43:47
Reply #10

niljut

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The OSL map Noise (Gabor) can be a pretty decent procedular map for stochastic flakes, I find. This is a quick test:


2020-01-21, 13:12:50
Reply #11

sprayer

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Yes, i put in refl color slot colors noise from photoshop. The others is the same as car paint shader for corona. Maru was made nice tutorial how to make normal maps flakes with corona scatter and you can color them for reflection and bake it as maps. Sadly i do not save the scene

2020-01-21, 20:53:09
Reply #12

cjwidd

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Right, I've seen that post before - I think and example was posted, actually.

2020-01-21, 21:50:58
Reply #13

cjwidd

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So one of the things that strikes me about flakes is that it is highly dependent on the lighting scenario, but also if you have filmic highlights or highlight compression enabled, you run the risk of totally flattening the effect. I'm sure this is obvious to everyone else, but it didn't occur to me until well into my tests.

2020-01-22, 00:55:55
Reply #14

cjwidd

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@Niljut and @Sprayer, are you able to share the shaders you've prepared to the forum? I'd like to study the graph, please.